<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
		
			.box{
				width: 300px;
				height: 40px;
				position: relative;
				border: 1px solid silver;
			}
			.box>input{
				width: 260px;
				height: 40px;
				box-sizing: border-box;
				border: none;
				outline: none;
			}
			.box:after{
				content: " ";
				display: block;
				position: absolute;
				width: 0px;
				height: 0px;
				border: 10px solid transparent;
				border-top-color: red;
				z-index: 10;
				right: 10px;
				top: 15px;
			}
			
		</style>
	</head>
	<body>
		<div class="box">
			<input type="text" />
		</div>
	
	</body>
</html>
